It is known that, when a sound wave emitted in a closed environment encounters a surface, a part of its energy passes through the surface, a part is absorbed by the impact with the surface and a part is reflected into the environment.
If an environment has a large reflective surface area, the acoustics in the environment may be greatly affected since the sound waves produced inside it are amplified with an effect similar to that of an echo.
In order to improve the acoustics of an environment without structural modifications, it is known to provide in the environment one or more sound-absorbing panels for absorbing most of the energy.
When correcting the acoustics, the internal surfaces of the environments are lined with sound-absorbing materials; these materials must have suitable characteristics not only from an acoustic but also from an aesthetic point of view since they must blend in with the architecture and the furnishings.
Sound-absorbing materials have the property that they absorb at least part of the acoustic energy and reduce the amount of energy which is reflected.
The known sound-absorbing panels, which are to be mounted for example on a wall, have a structure which is composed of a layer of foam (for example foam rubber), lined with a sheet, and kept rigid by a perimetral frame made of metal (for example aluminum), plastic or wood. The sheet is typically folded around the perimetral frame so as hide, at least on a visible side, stitches or other joints. However, when a sound-absorbing panel must have two visible sides, it is more difficult to conceal a joint in the sheet in a zone where two end portions of the sheet overlap.
In other known panels, the padding layer is combined with a rigid surface (for example made of metal, plastic or wood) which increases its rigidity and/or increases its acoustic performance. The rigid surface may be positioned on one side of the padding or inside the padding itself, creating a sandwich structure.
A first disadvantage of the sound-absorbing panels designed in accordance with the prior art consists in the presence of the frame or the support surface. They may in fact have a considerable weight and hence be difficult to handle, mount and support; moreover often the frame or the support surface are the most costly item of the panel.
Another disadvantage, as already mentioned, is that the sound-absorbing panels must have not only good sound-absorbing properties but also suitable aesthetic characteristics since they must blend in with the architecture and the furnishings. The frame and the joints between two end portions of a sheet used to cover the panel are undoubtedly negative elements which may create a lack of harmony with the surrounding environment.
Moreover, the frame (especially if made of metal) of a sound-absorbing panel does not act as a sound-absorbing material and often reduces the surface area of the sound-absorbing padding which can be effectively reached by the waves.
Moreover, sound-absorbing panels, the direction of which can be freely and easily adjusted, namely by means of simple operations can be arranged in different directions with respect to a wall or a ceiling of the environment where they are mounted, are not known. This constitutes a fairly major limitation because a better result in terms of sound-absorbing performance may be achieved by arranging the surface of the sound-absorbing panel as far as possible perpendicularly with respect to a sound source.
The technical problem is that of providing a sound-absorbing panel which is relatively simple to construct and install and which solves at least one of the abovementioned problems.